Test sample card

ABSTRACT

An improved sample card is provided. The improved card, typically used in biochemical analysis, achieves high sample well capacity and improved fluid flow, including by means of a plurality of through-channels which route the fluid flow of samples along both the front and back surfaces of the card. Elevated bubble traps are provided, as are integral interrupt slots for sensing card position and alignment. A bezeled leading edge facilitates insertion.

This is a divisional of application Ser. No. 08/455,534, filed May 31,1995, now U.S. Pat. No. 5,609,828.

FIELD OF THE INVENTION

The invention relates to an improved sample card for analyzingbiological or other samples.

BACKGROUND OF THE INVENTION

Biocards have been used to analyze blood or other biological samples ina spectroscopic or other automated reading machine. Such machinesreceive a small biocard, roughly the size of a playing card, in whichbiological reagents, nutrients or other material is deposited andsealed, prior to injection of patient samples.

The biocard contains the reagents and receives the patient samples in aseries of small wells, formed in the card in rows and columns andsealed, typically with tape on both sides. The biocards are filled withpatient sample material through fine hydraulic channels formed in thecard. The microorganisms in the samples may then be permitted to grow orreactions to proceed, generally over a period of up to a few hours,although the period varies with the type of bacteria or other substanceanalyzed and sample used.

After the incubation, the samples contained in the wells are placed infront of a laser, fluorescent light or other illumination source. Thecontent of the sample in a given well can then be deduced according toreadings on the spectrum, intensity or other characteristics of thetransmitted or reflected radiation, since the culture of differentbacteria or other agents leave distinctive signatures related toturbidity, density, byproducts, coloration, fluorescence and so forth.Biocards and machines for reading them of this general type for use inthese biochemical applications can for example be seen in U.S. Pat. Nos.4,318,994; 4,118,280; 4,116,775; 4,038,151; 4,018,652; and 3,957,583.

Despite the general success of biocards in this area, there is anongoing desire to improve the performance of the cards and readings ontheir samples. It is for example an advantage to impress more reactionwells in a given card, so that a greater variety of reactions andtherefore discrimination of samples can be realized. A given facilitymay have only one such machine, or be pressed for continuous analysis ofsamples of many patients, as at a large hospital. Conducting as manyidentifying reactions on each sample as possible is frequentlydesirable, yielding greater overall throughput.

However, biocards that have been exploited commercially have often beenlimited to a total of 30 sample wells (or 45 wells in some designs). Forcompatibility with existing reading machines, the cards generally cannot be enlarged from a certain standard profile (roughly 31/2" by21/4"). Total well capacity has accordingly not grown beyond theselevels, limiting the throughput on the machines.

It has also been the case that as the total number of reaction wells ona given card has increased, while the card size has remained constant,the wells have necessarily been formed increasingly close together. Withthe sample wells crowding each other on the card, it has become morelikely that the sample contained in one well can travel to the nextwell, to contaminate the second well. The threat of increasedcontamination comes into play especially as card well capacity increasesabove 30 wells.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide a biocard havingan increased number of sample wells.

It is another object of the invention to provide a biocard withincreased capacity, yet retaining overall standard card sizes.

It is another object of the invention to provide a biocard which can beloaded with samples quickly, easily and with a minimum of samplecorruption.

It is another object of the invention to provide a biocard with improveddisposal of injection bubbles arising during loading of the samples.

It is another object of the invention to provide a biocard whichincrease the effective fluid flow distance between adjacent wells,reducing well-to-well contamination.

It is another object of the invention to provide a biocard with better,smoother, more reliable fluid flow throughout the card.

The invention achieving these and other objects is an improved biocardhaving a significantly improved sample well capacity, easily achieving45 wells, and reaching 64 wells and feasibly more. The biocard of theinvention likewise provides carefully structured fluid channels whichimprove fluid flow, reduce bubbling yet improve disposal of any bubbleswhich do form through specially designed bubble traps.

The biocard of the invention provides, as well, improved securityagainst well-to-well contamination, in part by increasing the effectivedistance that the samples in adjacent sample wells must travel tocorrupt neighboring sites.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the drawings, in whichlike parts are labelled with like numbers. The drawings are brieflydescribed below.

FIG. 1 illustrates an improved biocard according to the invention, in afront planar view.

FIG. 2 illustrates the improved biocard according to the invention, in aback planar view.

FIG. 3 illustrates the improved biocard according to the invention, in atop edge view.

FIG. 4 illustrates the improved biocard according to the invention, in abottom edge view.

FIG. 5 illustrates the improved biocard according to the invention, in aside edge view.

FIG. 6 illustrates the improved biocard according to the invention, inan opposite side edge view.

FIG. 7 illustrates a sample well with associated fill channel and bubbletrap, according to the improved biocard to the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention is illustrated in FIGS. 1-7.This embodiment provides an improved biocard 100, having a generallyrectangular shape and in standard dimensions. Biocard 100 in theillustrated embodiment contains a total of 64 separate sample wells 110,each of which receives a sample, for example a biological sampleextracted from blood, other fluids, tissue or other material of apatient, for spectroscopic or other automated analysis. The biologicalsample may be a direct sample from the patient, or be patient samplewhich is extracted, diluted, suspended, or otherwise treated, insolution or otherwise. Other types of samples, including antibioticdosages or other material, can also be introduced for analysis. It willbe understood that well capacities other than 64 can be used. Biocard100 is generally used in a landscape orientation.

In terms of materials, biocard 100 may be made of polystyrene, PET, orany other suitable plastic or other material. Biocard 100 may betempered during manufacture with a softening material, so thatcrystalline rigidity, and resultant tendency to crack or chip, isreduced. Biocard 100 for instance may be manufactured out of a blend ofpolystyrene, approximately 90% or more, along with an additive of butylrubber to render the card slightly more flexible and resistant todamage. Biocard 100 may also be doped with coloring agents, for instancetitanium oxide to produce a white color, when desired.

The biocard 100 of the invention may be of use in identifying and/orenumerating any number of microorganisms, such as bacterial and/or otherbiological agents. Many bacteria lend themselves to automatedspectroscopic, fluorescent and similar analysis after incubation, as isknown in the art. The transmission and absorption of light is affectedby the turbidity, density and colormetric properties of the sample.Fluorescent reactions may be performed as well, independently or alongwith spectroscopic or other measurements. If fluorescent data aregathered, use of a coloring agent in biocard 100 is preferable, since anopaque card reduces or eliminates the scattering of fluorescentemissions throughout the card, as can occur with a translucent material.Other types of detection and analysis can be done on biocard 100,including testing of susceptibility of microorganisms to antibiotics ofdifferent types, and at different concentrations, so that biocard 100 isa general-purpose instrument.

To receive sample fluid, the biocard 100 includes a sample intake plenumor port 120 at an upper right corner of the card 100, located on aperimeter edge of the card. The sample wells of card 100 contain drybiological reagents which are previously put in place in the wells, byevaporative, freeze-drying or other means, prior to being dissolved insolution with the injected patient sample for analysis. Each well canhold a deposit of a different reagent, for identifying differentbiological agents, if desired.

Intake port 120 receives a fluid injection tip and related assembly(schematically illustrated as 130), through which the sample fluid orother solution which arrives to dissolve the biological reagent isinjected, under a vacuum pulled on biocard 100 (typically 0.7-0.9 PSIA),then released to atmospheric pressure. Injection port 120 includes asmall intake reservoir 140 formed as a roughly rectangular hole throughthe card 100, which receives incoming fluid, and acts as a fluid buffer.

The fluid (patient sample or other solution) enters intake port 120,collects in intake reservoir 140 and travels along first distributionchannel 150, located on the front or facing side of card 100. Firstdistribution channel 150 consists of a relatively long channel formed inthe surface of card 100, which extends substantially across the width ofthe card, and may have a cross section of approximately 0.1-0.2 mm².First distribution channel 150 is tapped at intervals along its lengthby a series of parallel distribution legs or fill channels 160, whichgenerally descend from channel 150 toward the sample wells 110 in eachof the eight illustrated columns. When the sample is injected into thecard, a short segment of the sample tip can be pinched off or heatsealed and left in place in intake port 120, acting as a sealing plug.

Fill channels 160 are relatively short channels (which may be kinked)which extend down from first distribution channel 140 into respectivesample wells 110 located in the first row of card 100, and having across section of approximately 0.1-0.2 mm².

It will be appreciated that each of fill channels 160 descend to andenter sample wells 110 at an angle, which results in the natural flow ofthe sample fluid down through the fill channels 160 by gravity, andresistance to small pieces of undissolved material flowing back up intothe fluid circuitry. When the sample fluid actually enters the well 110,the fluid fills the well by action of both gravity and a vortex-type offlow effect into that well. Also, any of the fill channels 160, asschematically illustrated in FIG. 7, as well as other connecting fluidchannels in the invention may be preferably formed in full-radius style,that is, as a semicircular conduit, rather than a squared-off channel asin some older designs. The full-radius feature has been found by theinventors to reduce friction and fluid turbulence, further enhancing theperformance of biocard 100.

Each of sample wells 110 in the first and other rows includes anassociated bubble trap 170, connected to sample well 110 at an uppercorner of the well, and located at a height slightly above the well onthe card surface. As illustrated in FIG. 7, each bubble trap 170 isconnected to its respective well by a short trap connecting conduit 180,formed as a hollow passage part-way into the card surface and forming ashort conducting path for trapped gaseous bubbles which have been formedin, or communicated to, the well 110 during the injection operation, bybacterial or other biological reaction, or otherwise. Bubble trap 170does not cut through the card completely, instead consisting of adepression or well of roughly cylindrical shape, with a rounded bottomcontour, and a volume of approximately 4.2 cubic mm in the illustratedembodiment.

Because the bubble trap 170 is located at an elevated position aboveeach respective well 110, any gaseous bubbles will tend to rise and betrapped in the depression of trap 170. With gaseous remnants led off tothe bubble trap 170, analytical readings on the biological sample can bemade more reliably, since scattering and other corruption of themicrobial radiation reading by gas is reduced or eliminated.

As will also be understood from the following, the two-sided nature ofbiocard 100 permits fluid channels to be formed opposite tonon-penetrating bubble traps 170, on the other side of the card. Someolder card designs have employed bubble traps which penetrate throughthe card, eliminating the possibility of surface channels being routedin their vicinity.

In addition to the introduction of fluid through the path of firstdistribution channel 150, fluid also travels to wells below the firstrow of wells through other directions. More specifically, intake port120 also connects to a second distribution channel 190 formed on theopposite or back surface of the biocard 100, second distribution channel190 also leading away from the intake reservoir 140. Second distributionchannel 190 also extends substantially along the width of card 100, buton the rear surface of the card. Second distribution channel 190 has across-sectional area of approximately 0.2-0.3 mm².

Second distribution channel 190 is tapped above each of the eightillustrated columns of sample wells by a triplet of additionaldistribution legs or channels 200. Each of triplet legs 200 containsthree relatively short connecting channels leading down from seconddistribution channel to a set of three respective through-channels 210formed through the body of card 100.

Through-channels 210 are small apertures, approximately 1 mm indiameter, formed cleanly through the body of biocard 100, formingconduits or vias from one surface of the card to the other. The channelsof triplet legs 200 connect to the respective through-channels 210,which in turn are connected to additional well fill channels 220,forming a short link to three additional respective samples wells 110.

However, the fill channels 220 deliver the fluid to the sample wellsfrom the opposite, that is rear, side of the card 100, creating adifferent fluid flow circuit which extends from intake port 120. Thatis, this path involves the second distribution channel on the rearsurface of the card, through the body of the card by way ofthrough-channels 210, then out to connecting fill channels 220 whichdeliver the sample to the well 110 (again at an inclined angle,providing gravity resistance to debris uptake).

The sample wells which receive the fluid from the second distributionthrough-channel circuit, like the sample wells which receive the fluidthrough the (front-planar) first distribution channel, also have bubbletraps 170 associated with them, in the same general above-wellconfiguration.

The biocard 100 therefore includes four rows by eight columns of samplewells built up by connecting channels through the first and seconddistribution channels. This provides a set of 32 sample wells. Inaddition, another contiguous set of samples wells, making up theremaining 32 wells for the total of 64, is also deployed along thebottom of the card body using through-channels.

More specifically, a third distribution channel 230 is in fluidconnection with intake port 120, but traces a generally vertical pathdownward from the port to a third distribution through-channel 240,located at a lower right section of the card 100. Third distributionchannel 230 and its corresponding third distribution through-channel 240have slightly larger cross sections than the first two distributionchannels and their through-channels 210, to accommodate larger fluidflow to a greater total number of destination wells (32, versus 8 and 24wells, respectively).

The fluid flows down through the third distribution channel 230, intothird distribution through-channel 240, and then splits into twosubchannels. The first subchannel 250 on third distribution channel 230,located on the rear of card 100, is a widthwise channel extending alongthe lower base of the card, having a cross-section of approximately0.2-0.3 mm². Rising up from first subchannel 250 are another set oftriplet legs 260, which generally resemble first triplet 200 but whichextend upward from first subchannel 230, rather than downward.

However, triplet legs 260 perform the same basic function, deliveringthe fluid to another set of through-channels 270, identical tothrough-channels 210. Through-channels 270 in turn lead through the cardbody, that is, to the front of the card, to connecting fill channels280, which are generally short concave links (which may be kinked) torespective additional sample wells 110. Fill channels 280 likewise enterthe sample wells 110 at an inclined angle, from above.

The last fluid flow path is second subchannel 290, leading off of thirddistribution through-channel 240 along the front of card 100, in agenerally horizontal or widthwise manner. Second subchannel 290 isconnected to the last (eighth), bottom row of eighth sample wells 110 byanother set of vertical connecting conduits 300, single conduitsconnecting to single wells. Conduits 300 are generally dog-legged instructure, enter the well at a slightly inclined angle, and theassociated wells each also include an associated bubble trap 170.

It may thus be seen that through the use of through-channels penetratingthe card body 110, along with carefully distributed links through aplurality of distribution channels, in the invention valuable surfacearea is freed up on the card, by allowing the necessary connectingchannels to be split up between the front and rear surfaces of the card.

The fluid flow paths thoroughly dispersed over card 100, including bothfront and rear surfaces, also result in a longer total linear travel ofthe flowing fluid than conventional cards. This leads to the significantadvantage that the possibility of inter-well contamination is reduced.The well-to-well distance in fact in the illustrated embodiment comes toapproximately 35 mm, significantly more than the 12 mm or so on manyolder card designs.

The inventors have also observed that the rate of inter-wellcontamination varies with the square of the linear distance, so theelongated fluid paths significantly enhance the integrity of readings onthe card. Contamination itself is a function of sample mixing (densityof solution falling out of wells) and liquid molecular diffusion, bothof which are discouraged by the relatively fine channel cross-sectionsin many sections of the overall fluid circuit, as well as overall pathlength.

The contamination rate is also reduced by the fact that the volume ofthe channels along the fluid circuit varies slightly along the overallcircuit travelled by a given sample. That is, the through-channels, thethree main distribution channels and other segments of the paths havecross-sectional areas which, although all relatively fine, may differslightly. The change in volume over the path tends to retard theprogression of contamination, as do dog-legged or kinked sections ofconnecting conduits.

All these structural adaptations cooperate in reducing the rate ofinter-well contamination in the biocard 100. The inventors have, as oneindication of contamination management, measured the time required fortest dye to infiltrate a neighboring well in conventional biocards andthe card of the invention. Contamination in a conventional,low-capacity, non-through-body card has been observed in approximately2-4 hours. In the biocard of the invention under similar conditions, incontrast, the contamination time has been observed at 16-18 hours.

Besides contamination kinematics, the upper-placed bubble traps 170 alsomore efficiently scrub the sample wells 110 of gas bubbles which formafter the sample injection. Samples are typically injected as noted byevacuating the card, introducing fluid at the intake and then releasingthe vacuum pull, so that the whole fluid circuitry returns toatmospheric pressure. Vacuum filling of the card may typically be doneover a period of 3-60 seconds, slower rates helping to reduce thetendency of bubbles to form. Those bubbles can ruin sample readings, soreducing them results in a smoother, more efficient, higher-capacity yetmore reliable biocard.

In addition, the improved fluid circuitry of biocard 100, includingfull-radius fill and other channels, generally narrower channels thanolder card designs, width-variation and other features result in a highcapture percentage of sample intake actually reaching the sample wells110, which the inventors have calculated at as high as 90-95%. Thiscompares with a capture percent in the 80s for older card designs.

For mechanical interaction with the automated reading machine, biocard100 may also be provided with a series of sensor stop holes 310, locatedalong the bottommost edge of the card. Sensor stop holes 310,illustrated as regularly spaced, rectangular through-holes, permitassociated photodetectors to detect when a biocard 100 mounted in areading machine has come into proper alignment for optical reading. Thesensor stop holes 310 are arranged in vertical register with thevertical columns of wells 110, so that the optical detection of the stophole 310 corresponds exactly to positioning of the sample wells 110before optical reading devices. Older biocards have been aligned bysensor holes which are formed not integrally with the card itself, butin carriages or other supports which are attached to the card at somepoint in the reading process, as for instance disclosed in U.S. Pat. No.4,118,280. These structures have however been prone to time-consumingmaintenance, particularly requiring the mechanical calibration andlining up of the carriage with the cards, and photodetectors. Integralsensor stop holes 310 eliminate that type of difficulty.

The biocard 100 of the invention is formed in the illustratedembodiment, as shown in FIG. 7, with a mold parting line 320 which isformed most of the way down into a sample well 110, toward the bottom ofthe card as opposing mold dies meet during manufacture. Older carddesigns often had the mold parting line, which forms a tiny lip in afluid cavity, at an upper point (above midway) of the card. The uppermold parting lines could tend to induce annular bubble rings to formduring filling, as well as reduce the efficiency of drying ofantibiotics or other material during manufacturing. The use of adownward offset mold parting line 320 avoids these difficulties, as wellas improving the efficiency of chemical or antibiotic dehydration duringincubation, and may act as a slight aperture during light andfluorescence reading operations. As illustrated in FIG. 7, the walls ofthe sample well, and other features, are usually formed at a slightangle or incline (typically 1°-4°), as an artifact of conventionalmolding processes in which separating the molded part from opposingmolding pieces is made easier with slight surface inclinations. Theshifting of the mold parting line 320 to the bottom area of biocard 100likewise results in a smaller inclined (roughly speaking, trapezoidal)area in the bottom of the sample well which can tend to trap material,slightly.

Another advantage of biocard 100 of the invention is that patient sampleand other markings are not introduced directly on the card itself, inpre-formed segments, as for example shown in aforementioned U.S. Pat.No. 4,116,775 and others. Those on-card stipplings and markings cancontribute to debris, mishandling and other problems. In the invention,instead, the card may be provided with bar-coding or other data markingsby adhesive media, but markings or pre-formed information segments arenot necessary (though some could be imprinted if desired) and debris,mishandling, loss of surface area and other problems can be avoided.

Biocard 100 furthermore includes, at the lower left corner of the cardas illustrated in FIG. 1, a tapered bezel edge 330. Tapered bezel edge330 provides an inclined surface for easier insertion of biocard 100into, carrousels or cassettes, into slots or bins for card reading, andother loading points in the processing of the card. Tapered bezel edge330 provides a gently inclined surface, which relieves the need fortight tolerances during loading operations.

Biocard 100 also includes a lower rail 360 and an upper rail 370, whichare slight structural "bulges" at along the top and bottom areas of thecard to reinforce the strength and enhance handling and loading of thebiocard 100. The extra width of lower and upper rails 360 and 370 alsoexceeds the thickness of sealing material, such as adhesive tape, thatis affixed to the front and back surfaces of biocard 100 for sealingduring manufacture and impregnation with reagents. The raised railstherefore protect that tape, especially edges from peeling, during themaking of the biocard 100, as well as during handling of the card,including during reading operations.

Upper rail 370 may have serrations 390 formed along its top edge, toprovide greater friction when biocard 100 is transported in card readingmachines or otherwise using belt drive mechanisms. Lower card rail 360may also have formed in it reduction cavities 380, which are smallelongated depressions which reduce the material, weight and expense ofthe card by carving out space where extra material is not necessary inthe reinforcing rail 360.

In terms of sealing of biocard 100 to contain reagents and othermaterial, it has been noted that sealing tapes are typically used toseal flush against biocard 100 from either side, with rail protection.Biocard 100 also includes a leading lip 340 on lower card rail 360, andon upper card rail 370 which projects slightly over the leading edge ofthe card. Conversely, at the opposite end of the biocard 100 there is atrailing truncation 350 in both rails. This structure permits sealingtape to be applied in the card preparation process in a continuousmanner, with card after card having tape applied, then the tape cutbetween successive cards without the tape from successive cards gettingstuck together. The leading lip 340 and trailing truncation 350 providesa clearance to separate cards and their applied tape, which may be cutat the trailing truncation 350 and wrapped back around the card edge,for increased security against interference between abutting cards.Thus, the trailing truncation or slanted ramp feature 350 ends slightlyinward from the extreme edge of the ends of the card, as shown in FIGS.1 and 2, to define a portion of the card surface or "shelf portion"between the ends of the ramps 350 and the extreme edge of the card 100,extending across the width of the card 100. This shelf portion providesa cutting surface for a blade cutting the tape applied to the card.Further, the ramp 350 facilites the stacking of multiple test samplecards without scuffing of the sealant tape applied to said cards, byallowing the ramps to slide over each other during a stacking motionwith the raised rails preventing scuffing of the tape.

The foregoing description of the improved biocard of the invention isillustrative, and variations on certain aspects of the inventive systemwill occur to persons skilled in the art. The scope of the invention isaccordingly intended to be limited only by the following claims.

We claim:
 1. A test sample card having plurality of sample wells influid communication with a fluid sample intake port, said test samplecard for containing a fluid sample subject to analysis by an opticalsystem, the improvement comprising:at least one aperture comprising anoptical sensor stop hole in said card positioned in registry with saidsample wells, whereby optical detection of said sensor stop hole by saidoptical system permits accurate alignment of said wells with saidoptical system as said test sample card moves relative to said opticalsystem for reading of said wells.
 2. The test sample card of claim 1,wherein said wells are arranged in a plurality of columns of wells, andwherein said improvement comprises an optical sensor stop hole placed inregistry with each of said columns of wells.
 3. The test sample card ofclaim 1, wherein said test sample card further comprises a peripheraledge portion, and wherein said at least one stop hole is locatedentirely within the test sample card in said peripheral edge portion. 4.The test sample card of claim 2, wherein said test sample card furthercomprises a peripheral edge portion, said columns of wells areequidistantly spaced from each other in an array of sample wells, andwherein said optical sensor stop holes are positioned in said peripheraledge portion and equidistantly spaced from one another in registry withsaid columns of wells.